Megohmmeters
Megohmmeters measure the insulation resistance of cables, motors, transformers and electrical installations. They apply a DC voltage of between 50 V and 10 kV, depending on the model, to detect current leakage, moisture, contamination or ageing of insulation. In maintenance, they can be used to diagnose insulation damage before a breakdown or short-circuit. In production, they guarantee equipment compliance with standards IEC 61557, IEC 61010 and EN 60204-1. Portable models provide rapid on-site measurements, while bench-top versions offer enhanced resolution for laboratories. Some instruments include automatic calculation of Polarisation Index (PI) and Dielectric Absorption Ratio (DAR) to qualify insulation quality. Internal memory, USB and Bluetooth interfaces make it easy to generate reports and trace ISO 17025 tests. Modern megohmmeters feature CAT III / CAT IV protection and high-visibility displays for safe use in the field.
It is an essential tool for preventing faults and ensuring the reliability of electrical installations.
SM7120
HIOKI
Megohmmeter / picoammeter with 2000V output voltage and 0.1fA resolution.
TOS8850
KIKUSUI
Insulation tester compliant with JIS, UL, CSA, CEE, BS and VDE standards.
CA6524
CHAUVIN ARNOUX
Insulation tester with capacitance measurement and IP54 enclosure.
CA6526
CHAUVIN ARNOUX
Insulation tester up to 1000V, capacitance measurement and Bluetooth.
practical questions about Megohmmeters
01
What is a megohmmeter used for?It measures the insulation resistance between conductors or between a conductor and earth, by applying a high voltage (generally between 250 V and 5,000 V DC) to detect insulation faults that could cause current leakage or electrical hazards.
02
What equipment can it be used on?It is used on cables, motors, transformers, switchboards or complete industrial installations. It prevents failures caused by moisture, contaminants or ageing insulation.
03
How should measurement results be interpreted?The expected values depend on the type of equipment tested, but low insulation (e.g. <1 MΩ) generally indicates a fault that needs to be dealt with. Some models offer dynamic diagnostics (PI, DAR) for a more detailed analysis of the insulation state over time.
04
Can testing damage the equipment?No, if the equipment is used correctly. It is essential to use the right voltage for the type of equipment being tested. Modern megohmmeters limit the energy injected to prevent any damage.
05
Are there digital versions with advanced functions?Yes, some models include built-in recorders, Bluetooth or USB interfaces for traceability, and programmable sequences for repetitive testing or QSE audits.
